This section provides background information related to the present disclosure which is not necessarily prior art.
For many polymer applications, such as packaging of light emitting diodes (LEDs) and other electronic devices, high thermal conductivity is an important property that assists with dissipating heat efficiently to maintain the functionality or reliability of a device or system. While uniaxially extended chain morphology has been shown to significantly enhance thermal conductivity in individual polymer chains and fibers, bulk polymers with thermodynamically favorable coiled and entangled chains have low thermal conductivities (e.g., κ=about 0.1 to about 0.4 W/m·K).
While the mechanisms of thermal transport in amorphous materials continue to be studied, it is generally believed that low thermal conductivities (κ) in plastics arise from highly inefficient packing of curvilinear polymer chains with bends, kinks and chain ends into an entangled structure with voids and weak inter-chain non-bonded (van der Waals, dipolar-dipolar) interactions. Thus, low thermal conductivities in bulk polymers are believed to occur due to entangled structures. Blending with high-κ fillers such as metal or ceramic particles, carbon nanotubes (CNTs), or graphene flakes is the most commonly used method to enhance thermal conductivity for materials that incorporate polymers that otherwise have low thermal conductivity. However, the large volume fraction of fillers required to achieve appreciable enhancement in thermal conductivity (κ) often leads to undesired optical or electrical properties, increased weight, high cost, or loss of the easy processability generally associated with polymers. Providing simple and inexpensive methods of forming bulk polymers with high thermal conductivity would be desirable.